Fuse disconnect switch



July 27, 1937. a. L. CARLISLE FUSE DISCONNECT SWITCH Filed March 13,1955 4 Sheets-Sheet l July 27, 1937. a. L. CARLISLE 2,088,152

FUSE DISCONNECT SWITCH Filed March 13, 1955 4 Sheets-Sheet 2 y 1937- a.L. CARLISLE 2,088,152

FUSE DI SCONNEC'I' SWITCH Filed March 13, 1935 4 Sheets-Sheet s y 1937-a. CARLISLE 2,088,152,

FUSE DISCONNECT SWITCH Filed March 13, 1955 4 Sheets-Sheet 4 UNITEDSTATES PATENT OFFICE;

2,088,152 FUSE mscoNNEc'r swrrcn George L. Carlisle, Greensburg, Pa.,assignor to Railway & Industrial Engineering Co., Greensburg, Pa., acorporation of Pennsylvania Application March 13, 1935, SerialNo.'10,949 In Canada February 2, 1934 43 Claims.

This invention relates to fused disconnect switches, and moreparticularly to combination devices in which the fuse and switch bladecomprise a single assembly.

The fuses and fused disconnect switches employed on high potential lineshave usually followed the general design of small cartridge fuses. Acommon construction has been an expulsion tube having end conductivesleeves to which the fuse wire was secured, one sleeve havingtrunnionsfor seating in a pair of hooked terminal arms while the othersleeve had opposite flat or curved faces that were received between apair of spring clamping fingers.

The contact areas at the ends of the fuse or fused switch were usuallyof substantial size, of the order of one or more square inches, and thecontact resistance was usually of uncertain magnitude and frequently wasrelatively high.

Objects of the present invention areto provide simple and rugged circuitbreakers of the fuse and/or fused disconnect switch type in which thefuse assembly is yieldingly held between two terminals by pressureexerted substantially axially of the fuse element, and in which thecontact areasat one or at both ends of the fuse element are of the orderof line or point contacts.

A further object is to provide a fused switch including an expulsiontube having end contacts adapted to be received in appropriate spacedterminals, a wire extending through the tube, and an explosive chargeformoving said wire out of the expulsion tube when an overload occurs.

A further object is to provide a fused -disconnect switch in which apivoted fuse assembly is normally held in approximately verticalposition by thepointcontact engagement of the relatively movable end ofthe fuse assembly with a pair of spring rods Or-terminal members.

other specific object is to provide a fused disconnect switch of theenclosed type in which the fuse element is mounted on the door of a fusebox, and in which the fuse assembly is so constructed that the doordrops to open position when the fuse blows.

More particularly, objects are to provide fused disconnect v switcheshaving the properties as above specified, and in which the fuse elementis not subjected to strain to retain the fused switch assembly inoperative position. These and other objects and advantages of theinvention will be apparent from the following specification when takenwith the accompanying drawings, in which:

Fig. 1 is a side view of one embodiment of the invention;

Fig. 2 is a front elevation of the same;

3 Figs. 3 and 4 are enlarged side views of the upper end of the switchblade assembly and the contact horn;

Fig. 5 isan enlarged side elevation of the lower terminal and of thelower or pivoted end of the switch blade assembly;

' Fig. 6 is a vertical section through-an enclosed fused switchembodying the invention; 1

Fig. '7 is a fragmentary section showing the latching terminal and latchin the opening position;

Fig. 8 is a side elevation of the assembly;

Fig. 9 is an inside view of the door and fuse assembly;

Fig. 10' is a front view, with parts in section, of the fuse box;

Figs-11 and 12 are sections on lines l Ill and The upper terminal strap3 clamps a contact horn to the top of the insulator I, the horncomprising a resilient rod 5 in the form of a loop which is reverselybent intermediate its ends to provide a resilient downwardly openingseat B for the reception of the switch blade, and. which terminates inan upwardly turned end I. The inner ends of the horn loop are rigidlyclamped by the strap 3, and the sides of the loop are spaced aparthorizontally to engage lugs on the fuse assembly. The lower terminal 4includes a pair of spaced arms which terminate in hooks 8, the mouth ofeach hook being of less width than the diameter of the alined circularopenings through the arms.

The insulator and itsterminal members will be recognized as constitutinga mounting for a fuse cartridge or a switch blade. A switch bladepivotally supported on the hooks 8 will be re- ,tained in closedposition by the, engagement of appropriate lugs with the latch portion 6of the contact horn, or a fuse cartridge may be supported betweenthecontact horn and the hooks 8. In accordance with the invention, aswitch blade assembly having the general form of an expulsion fuse ispivotally supported on the hooks 8 and is yieldingly latched to thecontact horn. Under normal conditions, the assembly serves as adisconnect switch and, in the case of an overload, the reaction due tothe blowing of the fuse releases the blade assembly from the latch andthe assembly drops to open position.

The switch blade assembly comprises an elongated expulsion tube 9 ofinsulating material to which upper and lower collars In, H are secured.A cover 12 is hinged to the upper collar III by a pin I3, and isprovided with a leaf spring N that slides over a projection 15 on thecollar III to latch the cover in closed position. The pivot I3 is spaceda substantial distance from the axis of the tube 9, and, at a somewhatshorter distance from that axis, the cover I2 is provided with a pair oflugs 16 for engagement in the latch seat 6 of the contact horn. A rib orfin l6 projects upwardly between the lugs IE to form a guide whichcenters the upper end of the fuse assembly between the spaced rodmembers 5 on which the seat 8 is formed. A ring I! is formed on thecollar 10 at the side opposite the pivot pin l3 and latching lugs Hi.

The lower collar II has a pair of trunnions l8 that are cut away, atopposite sides, to permit the trunnions to pass into the openings ofhooks B. A ring l9 at the inner side of the collar H has a bolt and awing nut 20 at its upper surface, and the outer portions of the ring arepreferably grooved to form a shallow seat.

The fuse element of the disconnect switch passes through the expulsiontube 9, its upper end being held against the upper collar ID by a boss2| on the cover l2, and its lower end being clamped to the lower collarby the wing nut 20. The fuse element is preferably of the explosivetype, and may take the form of a small cartridge housing an explosivecharge 22 through which an ignition wire 23 passes, one end of theignition wire being soldered to the conducting base 24 of the shell 24'and the other end being soldered to. a conducting wire 25 which has alength somewhat greater than that of the expulsion tube.

The explosive and the wires are retained in place by appropriate packingsuch as a wad 26 and wax 21. The explosive charge may be black powder orsmokeless powder and the ignition wire 23 may be a resistance wire, ofnickel, nichrome or the like, which is raised to the ignitiontemperature of the explosive, but not volatilized, by current flow inexcess of the rated capacity of the fuse. Alternatively, the wire 23 maybe of a relatively soft metal whichwill be volatilized, upon anexcessive flow of current, at a temperature substantially below theignition point of the explosive. When the wire 23 is of this lattertype, the fusion of the wire opens a gap in the conductive circuit andthe resulting arc ignites the explosive charge.

Reverting to Fig. 1 which shows the switch in normal closed position, itwill be noted that the latch seat 6 of the contact hook projects beyondthe hooks 3 in which the lower end of the fused blade is pivoted, andthat the spring pressure exerted upon the cover l2 holds the cover inclosed position since the latching lugs it are nearer the axis of thetube 9 than the pivot I3 of the cover l2. The blade assembly isyieldingly retained in the illustrated inclined position by the springpressure of the contact hook, and the switch may be opened and closed inthe usual manner by inserting the hook of a fuse puller or switchoperator in the upper ring l1,

Good electrical contacts between the blade assembly and the terminalmembers are provided by the point contact engagements between the lugsIE on the cover and the round rods which form the seat 6. At the lowerend of the assembly, the trunnions I8 may be given a slightly greatercurvature than that of the journals in the hooks 8 to provide linecontact engagement. Both the upper and the lower contact surfaces areself-cleaning since the cooperating parts wipe across each other whenthe fuse assembly is turned upwardly into operative position.

In the event of an overload, the wire 23 is heated to ignitiontemperature by the excessive current flow, thus igniting the explosivecharge. The circuit is broken adjacent the upper end of the tube 9 andthe high pressure within the tube quickly extinguishes any arc and blowsthe wire 23 from the tube. The recoil of the explosion tilts the coverl2 about its pivot l3, and this action carries the pivot pin 13 awayfrom the insulator i as the latching lugs it rock on the seat 6. Theeffect of this angular movement of the cover I2 is to increase thedistance from the lugs [6 to the axis of the tube 8 and, when thatdistance exceeds the spacing of pivot l3 from the axis, the springpressure on lugs l6 and gravity both operate to drop the blade assemblyto open position, as shown in 'dotted lines in Fig. 1.

The blade assembly may then be removed by inserting a fuse puller in thering l9 and lifting the trunnions l8 out of the hooks 8. The old fusecartridge is removed, and. a new one in serted, the wire 25 being passedthrough the tube 9, around the grooved seat in ring ill, and secured tothe lower collar by the wing nut 20. The assembly is then returned tothe hooks B, and the fused switch is closed by inserting a fuse pullerin hook I! and rotating the unit to engage the lugs IS in the seat ii ofthe contact hook.

The casing 30 of the enclosed i'used switch or cutout shown in Figs. 6to 14 is formed, as is customary, of a ceramic or other insulatingmaterial, and the mounting strap 30' is preferably so shaped that thecasing has a slight forward inclination to facilitate the automaticopening of the cover 3! when the fuse blows. One or both side walls ofthe casing are provided with hooded openings 32 for the introduction ofthe wires which are to be secured to the upper and lower terminals ofthe fused switch.

The upper terminal comprises a substantially rigid casting ofapproximately U-iorm, the central portion 33 of the casting beingrigidly bolted to the back wall of the casing and the spaced legs 34 ofthe casting terminate in notched ends that provide downwardly openingseats 35, the upper ends 36 of the terminal legs being forwardlyinclinedto guide the end of a fuse assembly into the seats.

The lower terminal is also of approximately U-shape and has a centralsection 31 which is rigidly secured, at its upper end, to a plate 38 ofbronze or other appropriate resilient material, and a stud bolt 39passes through the spring plate 38 and lower portion ll] of the terminalto mount these parts on the back wall of the casing. The nut M is notdrawn down tightly on bolt 39 and the adjacent portion 40 of theterminal is convex, thus permitting a limited rocking movement of theterminal upon the bolt. The side arms of the terminal 42 are deeplynotched by arcuate slots 43 to provide a pivotal seat for the fuse,assembly. Both terminals are provided with tubular portions 44 intowhich screws 45 extend to clamp the conductors to the terminals. A nameplate 48 may be secured to the lower terminal.

The door 3i has an integral pull ring and is preferably formed of amolded synthetic resin, the inner face of the door being deeply groovedto provide a recess, between the opposed flanges 41, in which theexpulsion tube 48 is mounted. The upper conductive collar 49 is fixed tothe tube 48 and has lugs 50 which are fixed to flanges 4'! by screws.The inner side of collar 49 has a pair of ears 5| in which the cover 52is pivotally mounted, the cover having a latch pin or crossbar 53 whichengages in the seat 35 of the upper terminal to retain the door inclosed position so long as the cover 52 is closed upon the upper end ofthe expulsion tube.

The lower' conducting member is an arcuate strap 54 which is bolted tothe cover 3| and has extensions or hubs 55 for pivotally mounting thedoor and fuse assembly in the journal slots 43 of the lower terminal.The strap carries a. bolt and wing nut 56 for clamping the lower endofthe removable fuse to the strap. A washer having'an extension 51 ispreferably provided to prevent any loosening of this clamped connection,the extension being received between spaced ears on the lower face ofthe strap. The fuse is preferably of the cartridge type, as described indetail in connection with Fig. 3.

As in the construction illustrated in Figs. 1 to 5 the pivotal axis ofthe cover 52 of the fuse assembly is so positioned, with respect to thelatch pin 53 and the hubs 55, that pressure exerted along the planepassing through these parts tends to hold the cover in closed position.The spacing "of the terminal seats is slightly less than the distancefrom the lower face of hubs 55 to the upper face of the latch pin 53whenthe cover is closed.

The lower terminal is therefore rocked downward, against the force ofthe spring plate 38. when the door 3| is moved into closed position. Thedoor may be readily closed, however, by a quick upward swing about thehubs 55, and the spring plate 38 then yieldingly locks the door inclosed position. A

When the fuse blows, the pressure within the expulsion tube 48 rocks thecover 52 into open position, as shown in Fig. '7, and this movementcarries the pivot point of the cover through a plane which extendsthrough the latch seats 35 and the journal slots 43, thus allowingthemomentarily increased stress in the spring plate 38 to cooperate withgravity to force the door 3i into open position. The dotted lines inFig. 6 illustrate the door in an intermediate position but it will beunderstood that the door swings into a vertical position when fullyopen. To refuse the device, the door is lifted from the lower terminal,the broken fuse wire and the cartridge are removed, and the new fusecartridge is inserted without removing the expulsion-tube from the.door.

The contact surfaces of the conducting members on the expulsion tube andon the terminals may be machined to somewhat different curva tures toprovide line contact engagements. The door and fuse assembly constitutethe blade member of a fused switch since the door may be lowerterminals.

The explosive fuse element presents the decided advantage that thecircuit is positively opened in a period which is substantiallyindependent of the relative magnitude of the overload. With the usualexpulsion fuses employing a'soft metal wire, a slight overload may meltthe wire but will fail to open the circuit if metal vapors are evolvedat such slow rate that the arc is not extinguished, Such arcing withinthe tube may be followed by current leakage along the inner wall of thetube and the proposed use of a special non-conducting coating on thetube wall has not proved en-- tirely satisfactory. It is to beunderstood, however, that soft metal wire fuses may. be used in thenovel fused disconnect switch when the load on the protected line is ofsuch a nature that any overload that may be anticipated will be of suchmagnitude as to eifect a rapid vaporization of a substantial part of thefused wire.

Particular attention is directed to thefact that the invention providesa drop-out fuse in which the fuse element is not subjected to anymechanical stress. Since the retention of the expulsion tube and fuseelement in the supporting terminals places no stress upon the fuseelement,

there is no change in the electrical properties of the fuse elementduring the useful life of the fuse. This feature is of particularimportance when the fuse element is formed of a relatively soft metal.

This application is a continuation-in-part of my copending applicationSer. No. 634,071, 'iiled Sept. 20, 1932. Claims specific to the enclosedtype of cutout, as illustrated in Figs. 6 to 14, have been presented ina divisional application, Ser. No. 125,503, filed Feb. 13, 1937.

While I have described preferred embodiments of the invention, it is' tobe understood that changes may be made in the several parts and in theirrelative size, shape and location, without departure from the spirit ofmy invention, as set forth in the following claims.

I claim:

1. A circuit breaker comprising a pair of .vertically spaced terminalshaving seat-defining portions presented towards each other, one of saidterminals including resilient means integral with the seat-definingportion thereof for yieldingly urging the seat defining portions of saidterminals towards each other, an elongated blade member having aconductive member at its lower end for engaging the seat-definingportion of said lower terminal to support the said blade member thereon,a conductive member at the upper end of said blade member and spacedfrom the lower conductive member to produce a pressure substantiallyalong the elongated blade member when the second conductive member ismanually forced into wedging engagement with the seat-defining portionof said upper terminal, and means supporting one of said conductivemembers and said blade member for relative movement, thereby tofacilitate the removal of the blade member from the upper terminal.

2. In a circuit breaker, the combination with a pair of verticallyspaced terminal members, a single insulator and means securing integralportions of'the respective terminal members to the opposite endstherebf, and spring means yieldingly urging a portion of the upperterminal member towards the lower terminal member, of a fuse assemblycomprising an elongated expul sion tube having a pair of axially spacedconductive members, a fuse extending through said tube and electricallyconnected between said conductive members, means for engaging theconductive members of the fuse assembly with the said terminal membersand with said spring means exerting pressure substantially axially ofthe fuse assembly, and means displaceable upon the blowing of said fuseto permit the ejection of the upper conductive member from the upperterminal member by the pressure exerted by said spring means.

3. In a fused circuit breaker, the combination with upper and lowerterminals having seats for receiving a fuse assembly, and spring meansfor pressing said seats towards each other for wedging the fuse assemblybetween said seats, of a fuse assembly comprising an elongatedinsulating tube having conductive means at the opposite ends thereof forpivotally supporting the tube on the lower seat and for wedgingengagement with the upper seat, whereby said fuse assembly is normallyretained in operative position by pressure exerted by said spring means,and fuse means extending through said tube, said fuse means having anenlarged head for seating upon the upper conductive means and a terminalwire adapted to be clamped to the lower conductive means, one of saidconductive means including a pivotally mounted member operable upon theblowing of the fuse means to permit the upper end of the fuse assemblyto drop from the upper seat by the combined effects of gravity and thepressure exerted on said fuse assembly by said spring means.

4. In a circuit breaker, a replaceable fuse assembly comprising anexpulsion tube, a conductive member pivotally supported at one end ofsaid tube and having a pair of laterally extending lugs, a conductivemember at the opposite end of said tube and having a pair of laterallyextending lugs, and a fuse extending through said tube and seriallyconnecting the said conductive members. the said lugs being adapted tosupport said fuse assembly between terminal members that arespring-pressed towards each lugs being spaced from the axis of saidtube.

5. In a circuit breaker, the combination with a pair of verticallyspaced terminals having seat portions for receiving a fuse assembly,insulating supporting means, and means rigidly securing each terminal tosaid supporting means, the upper terminal being resilient for yieldinglyurging said seat portions towards each other to exert pressuresubstantially along a fuse assembly seated between said terminals, of afuse assembly comprising an elongated tube of insulating material, aconductive collar on one end of said tube, a member pivoted on saidcollar and having means for engagement with the seat portion of one ofsaid terminals, a conductive memher on the other end of said tube andhaving means for engagement with the seat portion of the other terminal,and a fuse extending through said tube and serially'connected betweensaid pivoted member and said conductive member.

6. The invention as claimed in claim 5, wherein the seat-engaging meansof the said pivoted member is spaced from the pivotal axis thereof,whereby a pivotal movement of said member alters the distance betweenthe seat-engaging means on said pivoted member and the seatengagingmeans on said conductive member.

7. In a circuit breaker, the combination with a fuse assembly comprisingan elongated tube of insulating material, conductive members at each endof said tube and each having seating means for engaging a terminal, afuse, and

means for serially connecting said fuse between said conductive members,of terminal means for supporting said fuse assembly, said terminal meanscomprising a lower terminal having seat means for receiving the seatingmeans of one conductive member of said fuse assembly to pivotallysupport the fuse assembly on the lower terminal, and an upper terminalhaving a pair of parallel members rigidly secured thereto, the lowerfaces of said parallel members having seat portions adapted to receivethe seating means of the other conducting member of the fuse assemblywhen the latter is rotated upwardly into operative position, saidparallel members being resilient and yieldingly urged towards said seatmeans, whereby pressure exerted approximately along said fuse assemblyretains the latter in operative position between said terminals.

8. The invention as claimed in claim 7, wherein the seat portions ofsaid parallel members are spaced forwardly of a vertical plane throughsaid seat means of the lower terminal, whereby the fuse assembly issupported on said terminals in a forwardly inclined position.

9. The invention as claimed in claim '7, wherein said parallel membersare of resilient metal and constitute the means for yieldingly urgingsaid members towards said seat means of the lower terminals.

10. The invention as claimed in claim 7, wherein means is provided forpivotally mounting one of said conductive members upon said tube, saidpivotally mounted member being operable upon the blowing of a fuse torelease said fuse assembly from the upper terminal.

11. A circuit breaker comprising blade means, a pair of verticallyspaced terminal members, means on the lower terminal member providing apivotal support for one end of said blade means, and a seat on saidupper terminal member for receiving the other end of said blade meansand supporting the same in inclined position, said seat comprising apair of spaced resilient members.

12. A circuit breaker as claimed in claim 11, wherein said memberscomprise a single rod bent back upon itself.

13. A circuit breaker as claimed in claim 11, wherein the contactingsurfaces of said blade means and one of said terminal members aresurfaces of different curvature, whereby the contact engagement of saidsurfaces is of an order substantially less than surface contact.

14. A circuit breaker as'claimed in claim 11, wherein the contactingportions of said resilient members and said blade means are surfaces ofdifferent curvature, whereby the contact engagement between the same isrestricted to the order of line contacts.

15. A circuit breaker as claimed in claim 11, wherein said blade meanscomprises an expulsion tube of insulating material, a conductive memberat each end of said tube, a fuse element within said tube andelectrically connecting said conductive members, and means displaceableupon the blowing of said fuse element to permit the ejection of saidblade means from the upper terminal member by the force exerted by saidresilient members.

16. A circuit breaker as claimed in claim 11, wherein said resilientmembers are rods reversely bent to define the seat, the ends of the rodsflaring from each other to form a guide for the introduction of theblade means into the seat.

17. A circuit breaker as claimed in claim 11,

iii

accents wherein said resilient members are rods each having a portionfor rigid connection to an in sulator, and each bent to a complete loopbetween the seat and the connection portion thereof.

In 18. A circuit breaker comprising a cylindrical insulator, bracketmeans engaging an interme-= diate portion of said insulator for mountingthe terminal members, and spring means yieldinely said seats toward eachother to exert pressure approximately axially of said blade means, seatof the upperterminal member and the cooperating conductive portion oithe blade means comprising surfaces oi dihferent curvatures whereby thecontact engagement oi said suriaces is restricted to less than lullsurface contact. v i

so. A circuit breaker as claimed in claim it, wherein said upperterrninal member is resilient oi itself constitutes the spring" meanstor said. seats toward each other.

in circuit breaker, the combination with a vert cally arranged tubularinsulating" nieinber hav conductive members at the opposite endsthereoi, a closure for the upper end oi said tu= bills" insulatingmember, closure cent end oi the fuse engagement with an connectedbetween said conductive and supporting on s id. con ior reception in apair of *wrimi al a pair of vertically spaced terini portions definingseats winch to each other for receiving the re ve displace= s associatedhe suppo t is a;

seat to initiate removal or the in= from the upper tei nal seat,

as clamping exerted by yield 2 the ineinber nal seat. cult breaker asclaimed in claim 2i, the said portion of one terminal which es a seatconsists of spaced rod bers, and the said resilient rod members so thenieans yieldinsly tuning the said seats toiva ds each other.

2. in a fuse disconnect switch, palr oi spaced terminals, aninsulatincnienlber having conductive members at the opposite endsthereoi, means pivotally supportins'one oi said conduc tive members onone of said terminals, latch means ovably'rnounted on the second conduc=tive member for latching the same to said second terminal, a iuseelectrically connected between said conductive members, and means fordirectand havingnieans for pivotally supporting a re associatedconductive nieinber, ex rough said insulating member and means ing uponsaid latch means gaseous pressure developed by the blowing of said iuse,thereby to release said insulating member from one of said terminalsupon the blowing of the fuse.

24'. In a fuse disconnect switch, the combination with a pair of spacedterminals having seats for receiving the ends of a fuse assembly, atleast one terminal including spring means tending to force said seatstowards each other; oi

a fuse assembly comprising a tubular insulating member having conductivemembers at opposite ends thereof, means ior pivotally supporting one ofsaid conductive members on the seat of one of said tenals, a fuse withinsaid insulating member electrically co ected between said conductivemembers, and a latch member rnovably mounted on one conductive memberand normally positioned to latch the luse assembly in operative positionbetween the seats of said terminals, said latch member including anactuating por tion operable by the gaseous pressure developed by theblowing or the fuse to move said latch member out of latching position,thereby to per= unit the ejection of the fuse assembly from at least oneterminal by the pressure exerted by said spring means.

25. In a fuse disconnect switch, the cornbina= tion or a pair of spacedterminals, on expulsion tube supported on said terminals, a fuse exthrough said tube, a closure ior one end or and movably supported uponsaid tube, and means carried by said closure for latching engagementwith one oi said terminals, said latching engagement being destroyedwhen said closure moved by gaseous pressure developed Within said tubeby the blowing oi the ifuse.

26. A drop-out iused circuit breaker oi the type including a pair orvertically spaced ter= noinal niernbers each having contact moms, a fuseassembly comprising; an elongated expulsion tube housing a renewableiuse means and having a pair oi conductive members, said fuse meansextending through said tube and lrieins' electrlcallp connected betweensaid conductive mean here, and means for detachably said ruse assemblyupon said terminal members with the conductive members thereoi engaging"the respective contact means; characterized by the that the contactmeans otthe ter= in rial includes a resilie member havi' a lower surfacepresented s the contact neans the lower terminal, d resilient member constituti" spring means ior pressing s contact sovvards each other; theconduct their oi said ius assembly no ally so spaced that the contactmeans are forced apart against the iorce oi resilient member the upp rconductive inernber oi iuse assembly is forced beneath the said lowersur lace oi the upper contactnieans, and said ruse assembly includesmeans displaceable upon the blowing oi said iuse means to permit theelec tion oi said upper conductive rnern from the upper contact means bythe iorce exerted by said spring means.

27. in a fuse disconnect switch, the combinetion or" a pair or spacedterminals, on expulsion tube supported on said terminals, a fuse extendlug" throuuh saidtube, a closure for one end of said tube, means on saidclosure and engaging one of said terminals to form a yielding latch forretaining said tube in operative position between said terminals, andmeans supporting said closure on said tube for movement from its closedlatching position into an open latch-re leasing position, wherebymovement of the closure in response to the pressure developed by theblowing of said fuse releases said latch.

28. In a fuse disconnect switch, a pair of spaced terminals, oneterminal having a seat for receiving and pivotally supporting one end ofan expulsion tube and the other having a seat for receiving a latchelement, an expulsion tube having a conductive member at one end forengagement in said first terminal seat, a conductive closure member onand movably mounted across the other end of said tube, said closuremember including a latch element cooperating with said second terminalseat to retain said tube in operative position between said terminalswhen said closure member is in closed position, an explosive charge andan ignition wire at one end of saidtube, one end of said wire beingconnected electrically to the adjacent conductive member, and a wireconnecting said ignition wire to the other conductive member.

29. A gravity operated drop out fuse comprising a pair of spacedterminals, a seat on one terminal, a yielding contact member on theother terminal, a fuse support having at one end an element adapted tobe removably engaged in said seat to provide a pivotal mounting of saidtube on the seat terminal, a latch element at the other end of saidtubefor latching engagement with said yielding contact member when the saidother end of the tube is rotated upwardly to wedge said tube betweensaid terminals, a fuse element within said tube, and means on said tubeand movable by the pressure established within said tube when the fuseblows for moving said latch element out of engagement with said yieldingcontact member.

30. A fuse element comprising an expulsion tube having a conductivecollar at each end, a seat within one end of said tube for receiving anexplosive fuse cartridge, a latch member at the cartridge seat end ofsaid tube, means mounting the latch member upon the adjacent collar formovement in response to the reaction caused by the explosion of acartridge within said seat, trunnions on the collar at the opposite endof said tube, and clamping means on the collar at the opposite end ofsaid tube for receiving the terminal of a fuse link inserted in saidseat.

31. A fuse element as claimed in claim 30, wherein said mounting meanscomprises a piv oted closure for retaining a cartridge upon said.

seat, and said latch member is integral with said closure and lessremote from the axis of said tube than is the pivotal axis of saidclosure.

32. A fuse disconnect switch comprising a lower terminal having journalsthereiman upper terminal having a resilient contact horn projectingbeyond a vertical line through said journals, an expulsion tube having atrunnion at one end for reception in said journals, a closure for theopposite end of said tube and having a portion adapted to be forced intocontact with the lower face of: said contact horn to yieldingly retainsaid tube between said terminals and in an inclined position, and a fuseelement extend-- ing through said tube, said closure being pivoted onsaid tube for rotation about an axis offset from a line passing throughsaid journals and the portion of said resilient contact horn engaged bysaid closure.

33. The invention as set forth in claim 32, wherein said fuse elementcomprises an explosive cartridge seated in the upper end of said tubeand retained therein by said closure, an ignition wire in saidcartridge, and a flexible wire connected to said ignition wire andextending outside of the lower end of said tube for electricalconnection to said lower terminal.

34. Apparatus of the class described comprising an expulsion tube ofinsulating material, conducting members carried by and at each end ofthe tube, an explosive cartridge removably seated in one end of thetube, an end closure for retaining the cartridge in the tube, saidcartridge including an ignition wire contacting an explosive chargewithin a. shell and a conductor connected to said ignition wire andextended through said tube, and clamp means on the member remote fromsaid cartridge for clamping the conductor thereto.

35. The invention as set forth in claim 34, wherein said closure ispivotally mounted on the collar adjacent thereto and includes a terminalcontact portion less remote from the axis of the tube than the pivotalaxis of said closure.

36. In a fuse disconnect switch, a pair of spaced terminals, anexpulsion tube, a conductive member on one end of said tube and carryingtrunnions for pivotally mounting said tube on one of said terminals, apivoted closure for the other end of said tube, a fuse element extendingthrough said tube and having one end contacted by the closure when thelatter is in closed position, means for securing the opposite end ofsaid fuse element to said conductive member, and a contact horn foryieldingly receiving the said closure to support said tube between saidterminals, said horn and closure having cooperating portions which aremoved relatively to each other to release said closure from said hornwhen the closure is rotated by the gas pressure resulting from a blowingof the fuse element.

37. In a circuit breaker, an expulsion tube, a conductive closure forone end of said tube, a conductive member mounted on the opposite end ofsaid tube, an explosive cartridge retained in said tube by said closure,an ignition wire in said cartridge, and a conductor electricallyconnected to said ignition wire and extending through said tube forconnection with said conductive member.

38. In a fuse assembly of the character described, an elongatedinsulator, a hinge member on one end of the insulator, a fuse unitpivotally mounted on said hinge member, a terminal means secured to theopposite end of said insulator, said terminal means including a terminalseat for the fuse unit and a spring arm rigidly secured at one end tothe insulator, and a terminal on the fuse unit for engagement with saidseat.

39. A. fuse assembly as claimed in claim 38, wherein the cooperatingsurfaces oi the fuse unit terminal and of the terminal seat are bothcurved surfaces.

40. In a fused circuit breaker, the combination with a support ofinsulating material, a pair of connector elements secured in verticallyspaced relation on said support and having means for making connectionto line Wires, and means as sociated with each of said elements forestablishing an electrical connection to a fuse assembly, at least oneof said means including a pair of herb zontally spaced resilient membershaving their inner ends rigidly clamped to the associated connectorelement, the resilient members having lower surf-aces for engaging lugson a fuse assembly, of a fuse assembly including an expulsion tube and apair of contact members longttudinally spaced with respect to saidexpulsion tube, a fuse element extending through said tube and normallyelectrically connected between said contact members, and meanspivot-ally supporting said fuse assembly for angular movement intoapproximately vertical position to establish electrical connectionsbetween the contact members and said means associated with therespective connector elements.

41. A fused circuit breaker of the type including apair of. verticallyspaced terminals, a fuse assembly pivotally supported for movement intoapproximately vertical position 'to close a circuit between saidterminals, and means for latching said fuse assembly in saidapproximately vertical position, characterized by the fact that theupper terminal includes a member having means for establishingconnection to a line wire, and a pair of horizontally spaced resilientmembers having their inner ends rigidly secured to said member, saidresilient members being reversely bent to form seats'for receiving lugson the fuse assembly, whereby said resilient members comprise the latchmeans for latching the fuse assembly in approximately vertical position.

42. In a fused circuit breaker, the combination with an insulatingsupport and a pair of terminal means secured in vertically spacedrelation on said support, and means for establishing line wireconnections to said terminal means, the upper terminal means including aresilient member having a rigidly clamped inner end and a reversely bentresilient outer end, of a fuse assembly including an expulsion tube, afuse element extending through said tube, a closure for normallyretaining the upper end of the fuse element within said expulsion tube,and means pivotally supporting said fuse assembly for angular movementto carry said closure into engagement with the lower face of saidresilient member.

43. A fuse assembly as claimed in claim 42, wherein the contactingsurfaces of said resilient member and said expulsion tube closure havedifferent radii, whereby the contact engagement of said surfaces is lessthan surface contact.

GEORGE L. CARLISLE.

